Al Gore has three questions about climate change and our future. First: Do we have to change? Each day, global-warming pollution traps as much heat energy as would be released by 400,000 Hiroshima-class atomic bombs. This trapped heat is leading to stronger storms and more extreme floods, he says: "Every night on the TV news now is like a nature hike through the Book of Revelation." Second question: Can we change? We've already started. So then, the big question: Will we change? In this challenging, inspiring talk, Gore says yes. "When any great moral challenge is ultimately resolved into a binary choice between what is right and what is wrong, the outcome is foreordained because of who we are as human beings," he says. "That is why we're going to win this."